The present invention generally relates to fluid conditioning systems, and more particularly, to systems for cooling air and other fluids as well as to systems for removing humidity from air and simultaneously cooling of the dehumidified air for use in rooms, residences and commercial buildings where the system includes solid desiccating structures for humidity removal, the structures being continuously regenerated by a vacuum source.
While the systems of the present invention will be primarily discussed hereinafter with reference to their use in conjunction with the cooling and dehumidification of air, it should be recognized that their use and application are not thereby so limited. For example, the systems may be utilized in the cooling and dehumidification of other gaseous streams such as chemical process streams, natural gas flows and the like.
Heating, ventilation and cooling systems (commonly termed HVAC systems) are conventionally used in commercial and residential buildings and the like to condition the air within the building to a desired temperature and preferably to an optimal humidity. HVAC systems typically comprise a air handling unit which includes means for heating the air such as a furnace or the like, an evaporator connected to an exterior condenser unit which utilizes a compressed fluid such as a halohydrocarbon and a duct for connecting the heating means to the evaporator. In operation, a fan draws air from a return vent within the building and forces the air past the heating means and a coil of the evaporator. In a cooling mode of the system, the air is cooled as it passes over the evaporator coil and in a heating mode, the air is heated as it passes in heat exchange relationship with the heating means.
In conventional air conditioning systems used alone or in combination with heating means as in the above-described system, the condensing unit is located outside of the building to condense a working fluid contained in the system. Heat generated during the compression of the fluid is released to the atmosphere and the high pressure fluid is then conducted to the coil of the evaporator where it is expanded and thereby cooled. Air flowing past the evaporator coil is cooled by heat exchange with the working fluid. During cooling, humidity contained in the air tends to condense on the exterior surface of the evaporator coil and is collected and carried away to a drain or a point exterior to the building.
Several disadvantages are inherent with such systems, particularly in regard to the cooling portion of the system. As mentioned above, the working fluid for the cooling portion of a system is conventially a halohydrocarbon fluid such as those fluids sold under the trade name Freon. Such halohydrocarbon fluids, while generally functioning quite satisfactorily, have been linked to degradation of portions of the environment, particularly the ozone layer, when released into the atmosphere. In addition, such systems tend to be quite large and require significant amounts of energy for operation.
Furthermore such systems may not remove humidity contained in the air to the desired or optimal degree. Depending upon the residence contact time with the evaporator coil, the temperature of the coils and the amounts of humidity contained in the air among other factors, the conditioned air exiting from the system may contain excess humidity for optimum comfort within the building. It has been proposed that such systems and other air conditioning systems include solid or liquid desiccating material as a means for controlling humidity in the air. While such systems do tend to remove some of the humidity from the air satisfactorily, the desiccating material must be regenerated on the periodic basis, generally by evaporating the contained water by the application of heat to the material. As is apparent, the regeneration step for the desiccating material significantly adds to the energy costs associated with the operation of the air conditioning system.